ε-Caprolactone or simply caprolactone is a cyclic ester, a member of the lactone family, with a seven-membered ring with the formula (CH2)5CO2. This colorless liquid is miscible with most organic solvents. It is produced on a very large scale as a precursor to caprolactam.
| Caprolactone | |
|---|---|
 |
|
|
2-oxepanone |
|
|
Other names
epsilon-caprolactone |
|
| Identifiers | |
| CAS number | 502-44-3  |
| ChemSpider | 9972 |
| KEGG | C01880 |
| ChEBI | CHEBI:17915 |
| ChEMBL | CHEMBL373123 |
| Jmol-3D images | Image 1 |
|
|
|
|
| Properties | |
| Molecular formula | C6H10O2 |
| Molar mass | 114.14 g/mol |
| Density | 1.030 g/cm3 |
| Melting point |
-1 °C, 272 K, 30 °F |
| Boiling point |
253 °C, 526 K, 487 °F ([1]) |
 (verify) (what is:  / ?)Except where noted otherwise, data are given for materials in their standard state (at 25 °C, 100 kPa) |
|
| Infobox references | |
ε-Caprolactone or simply caprolactone is a cyclic ester, a member of the lactone family, with a seven-membered ring with the formula (CH2)5CO2. This colorless liquid is miscible with most organic solvents. It is produced on a very large scale as a precursor to caprolactam.
Contents |
Production and uses [edit]
The great majority of caprolactone is consumed, often in situ, as a precursor to caprolactam.[2] It is also a monomer used in the manufacture of highly specialised polymers. Ring-opening polymerization, for example, gives polycaprolactone.[3] Another polymer is polyglecaprone, used as suture material in surgery.[4]
Caprolactone is prepared industrially by Baeyer-Villiger oxidation of cyclohexanone with peracetic acid. The three main manufacturers are BASF in the USA, Daicel in Japan and the largest Perstorp in the UK.
Reactions [edit]
The dominant reaction for caprolactone is its conversion to caprolactam, billions of kilograms of which are produced annually. Caprolactone is treated with ammonia at elevated temperatures to give the lactam:
- (CH2)5CO2 + NH3 → (CH2)5C(O)NH + H2O
Carbonylation of caprolactone gives, after hydrolysis, pimelic acid. The lactone ring is easily opened with nucleophiles including alcohols and water to give polylactones and eventually the 6-hydroxyadipic acid.
Related compounds [edit]
Several other caprolactones are known, although none approaches the technological importance of ε-caprolactone. These isomers include alpha-, beta-, gamma-, delta-caprolactones. All are chiral. Gamma-caprolactone is component of flower aromas and an insect pheromone.[5] delta-Caprolactone is found in heated milk fat.[6]
Safety [edit]
Caprolactone hydrolyses rapidly and the resulting hydroxycarboxylic acid displays unexceptional toxicity, as is common for the other hydroxycarboxylic acids.[7] It is known to cause severe eye irritation. Exposure may result in corneal injury.
References [edit]
- ^ OECD SIDS [www.chem.unep.ch/irptc/sids/OECDSIDS/502443.pdf 502443 - epsilon-caprolactone]
- ^ Josef Ritz, Hugo Fuchs, Heinz Kieczka, William C. Moran "Caprolactam" in Ullmann's Encyclopedia of Industrial Chemistry 2002, Wiley-VCH, Weinheim. doi:10.1002/14356007.a05_031
- ^ Horst Köpnick, Manfred Schmidt, Wilhelm Brügging, Jörn Rüter, Walter Kaminsky "Polyesters" in Ullmann's Encyclopedia of Industrial Chemistry 2002, Wiley-VCH, Weinheim. doi:10.1002/14356007.a21_227
- ^ http://www.curehunter.com/public/keywordSummaryC095495-glycolide-E-caprolactone-copolymer.do
- ^ Leading reference: M. Teresa Nunez, Victor S. Martin (1990), Efficient oxidation of phenyl groups to carboxylic acids with ruthenium tetraoxide. A simple synthesis of (R)-gamma-caprolactone, the pheromone of Trogoderma granarium. Journal of Organic Chemistry, 1990, Volume 55, Issue 6, pp 1928–1932. doi:10.1021/jo00293a044
- ^ Thomas H. Parliament, Wassef W. Nawar and Irving S. Fagerson (1965), Delta-Caprolactone in Heated Milk Fat Journal of Dairy Science Vol. 48 No. 5 pages 615-616.
- ^ Karlheinz Miltenberger "Hydroxycarboxylic Acids, Aliphatic" in Ullmann's Encyclopedia of Industrial Chemistry, Wiley-VCH, Weinheim, 2005. doi:10.1002/14356007.a13_507
